The present invention generally relates to a method of making plates or profiled workpieces from annual plants, such as flax, straw, hemp, rice, reed, sugar cane, cotton stem, and in particular is directed to a method in which the plant parts are comminuted, glued and subsequently pressed.
A conventional method for fabricating plates or boards of straw is known in which straw obtained during harvesting of grain is pressed into bales, and the bales are subsequently stored. Evidently, a harvesting of large grain fields results in a respectively large number of straw bales so that storage of such bales for protection against weather influence poses a significant problem. As roofed storage spaces are normally not available for such quantities of straw bales, the straw bales are stored outdoors. Even when covering the bales by canvases or wrappings, the moisture content of the bales during storage will in some areas substantially increase thereby diminishing the quality of the raw material for fabrication of the plates. Also, the quality on the outside of the bale stack may also be adversely affected when stored outdoors through incident ultraviolet radiation.
In the event, the raw material obtained from annual plants for fabrication of plates or profiled workpieces has a high moisture content and/or variances in moisture content, the process requires the provision of a separate dryer. Apart from the high energy consumption for conducting a drying operation, the additional arrangement of a dryer necessitates a cleaning of exhaust air to prevent release of harmful agents into the environment. Normally, this is done by incorporating a vent discharge and dedusting unit which exhibits an air throughput of 20,000 m.sup.3 /h already for a small dryer with an output of 14 dlh.